Area Forecast Discussion
Issued by NWS Central Illinois

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283
FXUS63 KILX 232007
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
307 PM CDT Wed May 23 2018

.SHORT TERM...(This evening through Thursday night)
ISSUED AT 300 PM CDT Wed May 23 2018

Fair and dry weather expected to continue across central and
southeast IL through Thursday night. Upper level ridge over the MS
river valley and IL through Thursday along with surface high
pressure ridge spreading across the southern Great Lakes and into
the mid Atlantic States, will keep it dry with fair skies. Few to
scattered cumulus clouds with bases of 4-5k ft from Galesburg to
Springfield west will diminish and/or retreat to the west late
this afternoon and early evening with east winds bringing in drier
air as dewpoints slip into the 50s. Drier air will also limit
patchy shallow ground fog formation toward daybreak and left out
of forecast. Lows overnight in the lower 60s, with some upper 50s
over drier air (dewpoints in the lower 50s) from Bloomington and
Champaign ne. Temps currently in the low to mid 80s across CWA.
Expect temps to rise a few degrees higher tomorrow with highs in
the mid to upper 80s with ample sunshine, warmest in western CWA
where 850 mb temps around 16C. Humidity levels stay fair low yet
on Thu with dewpoints in the mid to upper 50s central and eastern
IL, and lower 60s in western CWA. Lows Thu night of 60-65F, with
coolest readings around 60F in east central IL and mildest western
CWA.

&&

.LONG TERM...(Friday through Wednesday)
ISSUED AT 300 PM CDT Wed May 23 2018

An upper level trof over the Northwest US and northern Rockies to
open up/weaken as it moves east to WI and the IA/IL border by
sunset Friday. Surface high moves off the mid Atlantic States
Friday with a southerly flow bringing very warm and starting to
bring in more humid air. Highs Friday in the upper 80s with
dewpoints elevating into the low to mid 60s. Isolated showers and
thunderstorms possible from I-55 west Friday afternoon/evening.
Isolated convection possible in eastern IL too overnight Friday
night. Have 20-30% chance of convection on Saturday as weakening
upper level trof moves through, and into the Ohio river valley by
Sat night. Have 30% pops from I-55 east by Sat afternoon with 20%
west of I-55 on Saturday. Highs Sat in the upper 80s to near 90F
with afternoon heat indices of 90-95F.

Isolated convection could linger in southeast IL Sat night and
Sunday with another very warm and rather humid day with highs in
the upper 80s and lower 90s and afternoon heat indices of 90-95F.
Models have trended drier Sunday night through Monday as upper
level ridge builds back over IL. Summerlike heat and humidity to
likely prevail through next Wed with highs in the upper 80s to
near 90F. A weak cutoff upper level low lifting slowly northward
over the gulf of Mexico and into the southeast states by middle of
next week could return isolated convection to southeast IL by Tue
afternoon and over the CWA by next Wed.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1240 PM CDT Wed May 23 2018

VFR conditions forecast to continue across the central IL airports
through 18Z/1 pm Thu. 1024 mb high pressure over Lake MI and
ridging sw into IL/MO will drift over the southern Great Lakes by
18Z/Thu while upper level ridge builds over the MS river valley
including IL. This will continue fair and dry weather across
central IL through Thu. Models shows some cumulus clouds from
Galesburg to Springfield west into mid afternoon and then drifting
further west later this afternoon as drier air moves in from the
ENE. East to ENE winds less than 10 kts this afternoon to be light
tonight and veer SE at 5-8 kts after 14Z/9 am Thu. Latest CAM
models are not showing any fog formation overnight across central
IL airports with drier dewpoints advecting in from the east.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...07
LONG TERM...07
AVIATION...07



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